The world has come together this week in Cancún, Mexico, to forge a collective response to climate change. One year on from the belly-flop in Copenhagen, some voices are questioning the viability of the UN process.

While those questioning the process are ill-informed and playing into the hands of climate sceptics, it is also true that we are still far from reaching an actual consensus on the way ahead. This is a prospect that makes millions of poor people on the frontlines of climate change nervous.

This year's deadly torrential rains in Pakistan have caused devastation for millions, ravaging crops and water supplies across the country. The intense heatwave in Russia hit harvests hard. Both of these events – besides the damage they caused, have also contributed to rocketing wheat and other agricultural prices around the world. Scientists predict such extreme weather events signal to the shape of things to evolve.

Imagine if such devastations were to start occurring simultaneously in many parts of the world. No international funding mechanism could bear the cost of rehabilitation from such damages.

This fortnight's conference will be critically important for restoring trust between developed and developing nations in the fight against climate change. While a legally binding international treaty is not expected in Cancún, we can hope for – and expect – decisions in critical areas, such as the technology mechanism, adaptation framework, transparency in efforts to reduce emissions, accounting for emissions from forestry and, most crucially, the establishment of new funds and proper governance of climate finance. Such key decisions would pave the way for a more comprehensive deal next year.

The Copenhagen accord, despite its weakness, controversy, and inadequacy, did manage to stitch together a bare-bones agreement on climate finance, both in the short- and long-term. In the short term, developed countries committed to provide "new and additional" resources to developing countries approaching US $30bn from 2010-2012, balanced for helping them to adapt to climate change and to manage the growth in their emissions.

There's no mystery to what developing countries expect in Cancún: evidence that promises have been kept, and new finance being delivered.

It is ironic that those very countries that support the formalisation of the Copenhagen accord are not following the principles they themselves laid down in that document. The evidence so far suggests that only a small portion of what is pledged is really new, the major portion consists of recycled commitments, such as those that were made to meet the millennium development goals. This will only widen the chasm in trust deficit that has crippled the negotiations.

What's more, a worryingly high proportion is being channeled in the form of loans, not grants. Grants are essential to support the adaptation needs of the poorest and most vulnerable, in particular. The last thing poor countries need is to be saddled with new debt obligations.

Several developed countries, including the USA and EU nations, plan to release reports in Cancún outlining their allocation of "fast-start finance". The developing world sincerely hopes their reports show whether the money pledged is being delivered as it should and whether or not we are following the principles we agreed to in the Copenhagen accord.

The fast-start finance'experience has already taught us one lesson. In the long run, relying on voluntary reports from developed countries is a recipe for disaster and growing mistrust. To really show they are serious, developed countries should join with developing countries in Cancún to establish a framework to oversee long-term global climate finance flows, according to fair, common standards.

We should focus on strengthening the role of multilateral institutions, such as the adaptation fund in channeling the adaptation resources.Estimates suggest less than 10% of current climate finance flows are going to support adaptation. That can't continue.

It's imperative that developed countries use the opportunity of fast start finance to bridge the trust deficit and move the world towards the ultimate goal: halting the most dangerous effects of climate change. For those picking up the pieces in Pakistan and Russia, nothing less is acceptable.

• Farrukh Iqbal Khan is lead negotiator on climate change for Pakistan